I think evil spirit is called 'Pei'. If what I say is correct we tend to believe that it exists. For, most of us believe in good spirit which means something divine.
If we call something good, then we knowingly or unknowingly acknowledge something which is bad.
But I question its existence.
Good or bad, Pei or divine, all these are something abstract. So we can not see, touch, and smell. But it could be very well experienced. When we get pleasant feeling, seeing something or being with something or somebody, we say it is good or divine. When we get bitter feeling seeing something or somebody it we say it is bad or evil.
Seeing a nude image someone says that it is bad and another says that it is a nice art. One element is considered both good and evil. How could it be? It is just because that something is in the site of the viewer. Element is same. But different viewers view the one and same element differently. So, I am certain that good or bad are in the understanidng of the viewer.
If we are well disposed then we tend to understand everything good. If not we tend to say that everything is bad.
If we have only positive or pleasant feelings or thinking, then there will not be any room for evil or Pei.